A standard reproducible method for determining the potency of inactivated poliovirus (IPV) vaccines in vitro would be an important advance toward the eradication of polio. Protection against polio is provided by neutralizing antibodies with "D" antigen specificity. We have developed an ELISA test in which polyclonal antibody (which is "D" specific) is used for detection. Using our reagents as the standard we examined sera from other collaborating laboratories for the ability to measure the potency of IPV vaccines. We were able to examine polyclonal sera prepared in four different species including: rabbits, cows, horses and goats. We were also able to compare two different vaccine preparations of IPV, one made from wild poliovirus strains and the other from Sabin strains. Furthermore, we were able to examine reagents prepared with either the wildtype or Sabin strains of poliovirus. We have completed our evaluation of the available polyclonal sera and are in the process of evaluating different monoclonal antibodies with the various polyclonal antibodies. We have found that reagents prepared against wildtype poliovirus strains work in the ELISA assay with Sabin derived IPV and vice versa. These findings suggest that the attenuated strains (Sabin) when prepared as an inactivated vaccine retain antigens in common with the inactivated wildtype strains. Whether equivalent amounts of D antigen units used to formulate trivalent IPV derived from wildtype strains is necessary for IPV derived from Sabin strains is not yet known. We plan to continue with this evaluation and to include in vivo studies of potency in parallel with the ELISA evaluation. In addition, the sera will be tested in our laboratory for neutralizing antibodies. The site-specificity of our monoclonal antibodies will be determined by one of our collaborators.